In the case of integrated circuits in security-relevant applications, there arises the difficulty of having to protect the circuits against attacks which are intended to covertly discover or analyze the circuit in question, for example by means of FIB (Focused Ion Beam). Optical or mechanical analysis methods are also used.
There are already a number of security concepts with which the integrated circuits can be protected against such attacks, in particular can be provided with a shield in which, for example, active components are used in order to shield an external attack on the circuit. However, the risk of analyzing the circuits from the rear side of a semiconductor chip, i.e. through the semiconductor substrate, has hitherto been ignored.
It is possible to subject an integrated circuit to an analysis, the so-called “Reverse Engineering”. This analysis can be used to analyse the method of operation or else to influence the method of operation for the purpose of manipulating data contents or the operating sequence.
For the purpose of the analysis, the material which covers the surface of the chip is dissolved, for example. This material may be either a plastic molding compound, which forms the housing of the semiconductor component, or a so-called “Globe Top”, which is used merely to protect the surface of the chip and the electrical connections against mechanical damage. After the material which covers or surrounds the semiconductor chip has been removed, the passivation layer of the semiconductor chip is generally accessible. The layer may be selectively removed by means of etching methods, laser or FIB (Focused Ion Beam) methods. Removing the respective exposed layer in layers and photographing the latter makes it possible to subsequently analyze the structure of the integrated circuit.
So that individual layers cannot be removed using grinding methods such that they can be completely analyzed, the applicant is aware of methods for producing integrated circuit arrangements in which the substrate, on which an integrated circuit is formed, is nonplanar at least in one propagation direction. However, the protective layer which covers the integrated circuit arrangement can still be removed using etching methods so that it is possible to access those layers of the substrate which have the integrated circuit.